Cylinder-lock.



J. R. FLETCHER. CYLINDER LOOK. APPLICATION IILBD SEPT. 19, 1913.

1,099,903, Patented June 9, 191i WITNESSES [m 4 i i BY IN VEN TOR. James R. Fletcher:

A TTORNE Y.

COLUMBIA PLANOGRAPH C0.,WASHINOTON, D. G.

'Iv ED STATES PATENT OFFICE.

JAMES R. FLETCHER, OF NEW- BRITAIN, CONNECTICUT, ASSIGNOR TO THE AMERICAN HARDWARE CORPORATION, OF NEW BRITAIN, CONNECTICUT, A CORPORATION OF CONNECTICUT.

CYLINDER-LOCK.

Specification of Letters Patent.

Application filed September 19, 1913.

Patented J 11116 9, 1914. Serial No. 790,638.

To all whom it may concern-7 Be it known that I, JAMES R. FLETCHER, a citizen of the United States, and a resident of New Britain, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Cylinder-Locks, of which the following is a specification.

This invention relates particularly to improvements in the key plug and its method of manufacture and has for its object to produce a plug of hard or temperable metal which will withstand the excessive wear which is incident to certain installations due to the continual use of the key.

In drawings Figure 1 is a view of the cylinder in cross section. Fig. 2 is a plan view thereof. Fig. 3 is a top and side view of the unfinished plug. Fig. 4 is a sectional View of the plug being swaged to finished shape. Fig. 5 is a side View of the plug, showing a finishing operation. Fig. 6 is a side view of the finished plug.

Heretofore it has been customary to make the cylinder and key plug of locks of this type of brass or bronze both of which are relatively soft. In many instances in public and semi-public buildings a lock is more or less continuously used, subjecting the key plug to an unusual amount of wear which the soft metal of the plug cannot stand without yielding or wearing in one or more places, with the result that the moving parts of the locks and the key get out of alinement. It has heretofore been proposed to reinforce certain parts of the plug by inserting bushings and plates of hardened metal at those points subjected to greatest wear, but there are obvious objections to such methods. The peculiar shape of the plug and the irregular profile of the keyway have heretofore necessitated the use of relatively soft metal in its manufacture.

By this invention and the novel method of manufacture herein illustrated and described, it is possible to make the plug of a metal which is relatively harder than the metal of the cylinder or key and preferably of a metal susceptible of tempering or hardening in order that it may withstand excessive wear.

Referring to the drawings, a denotes the cylinder 1) the plug and e the pin tumblers held in projected position by springs d, all as is usual in looks of this type.

I have not illustrated or described the detailed features of construction of a lock since my invention is concerned only with the plug.

The plug 12 is made of a metal which is relatively harder than the cylinder and may conveniently be cast in malleable iron and then finished and if desired hardened. The particular method of manufacture which has been found to be practical and to produce the desired result is as follows: First, the plug blank is cast in the form shown in Fig. 3 with the longitudinal groove 5 in one side. Next the blank is swaged down in suitable dies upon a hardened steel pattern whose cross section corresponds to the desired profile of the key-way, giving to the key-way the proper shape and size and smoothing off any bur or unevenness which may be there. Next the plug is turned down to proper size to accurately fit in place in the cylinder; and finally it is case-hardened whenever de sired. In this way I am enabled to produce a plug from hard metal such as iron or steel and to accurately form, shape and finish the plug and the key-way in it. It may not always be necessary to turn down the plug or harden it, though it will usually be desirable.

I desire it to be understood that it is my intention to include in the appended claims such modifications and alterations as come fairly within the scope of the invention.

I claim as my invention 1. As a new article of manufacture a key plug of integral structure formed from a metal capable of being hardened, and provided with a longitudinal key-way of irregular profile.

2. In a cylinder lock a cylinder, key plug, and key, said plug being relatively harder than said cylinder and key, and having a longitudinal key-way of irregular profile and comprising an integral structure formed from a metal capable of being hardened.

JAMES R. FLETCHER.

Witnesses:

F. G. HAUsMANN, CLAYTON A. PARKER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

